We have just deployed an Exchange 2007 server to work behind our Exchange 2003 Master server and we are getting the following events in the Exchange 2003 server event log when we are trying to sync a mobile device with a users mailbox on the Exchange 2007 server:
Event ID: 3005
Source: Server ActiveSync
Unexpected Exchange mailbox Server error: Server: [s-ledec1.yorkshire-enterprise.co.uk] User: [Tommy.Tester@yfmgroup.co.uk] HTTP status code: [503]. Verify that the Exchange mailbox Server is working correctly.